These two Blister Beetles were found together within the same Yucca baccata flower suggesting that they are color morphs
of the same species. McDowell Mts., Maricopa
County, Arizona, USA. 5 April 2016.

Meloidae, or Blister Beetles, are common
insects found on flowers especially during spring in the Sonoran Desert.
They feed on the petals and pollen as adults but live an entirely different
life as immature larvae. The adults tend to have bright,
aposomatic coloration set off by black. This is a warning that these
beetles often contain noxious or poisonous compounds; birds and other
insectivores tend to avoid meloids.

The larvae are parasitic in the nests of ground nesting bees
or other ground nesting insects. The tiny, first stage larvae are mobile and
seek out a suitable host. Once they attach to a host they become immobile
drawing sustenance as they grow.

Zonitis, one genus of Meloidae, has many described species that are difficult to separate. Some are difficult
to distinguish from the related genus Nemognatha.